JPH0153190B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charge-controlled inkjet recording device, and more particularly to a printing object speed tracking device that controls printing timing.

In recent years, inkjet recording devices have been increasingly used as computer output terminals or as devices for directly printing dates, serial numbers, etc. on products during the production process because of their ability to perform non-contact, high-speed printing. This device supplies ink under pressure to a nozzle and atomizes the ink by applying vibrations at a constant frequency. At this time, a predetermined pattern is recorded on the recording material by appropriately charging the particles and electrically deflecting them. Inkjet recording, which is generally used for industrial purposes, is performed by deflection scanning in the vertical direction by charge control and relative horizontal movement between the object to be printed and the recording head, and is usually performed while the object to be printed is conveyed on a conveyor. There is. Therefore, the width of a printed character is determined by the printing speed of the inkjet recording device and the speed of the conveyor. The influence of conveyor speed fluctuations on character quality within ±10% is hardly a problem, and a typical constant speed conveyor satisfies this condition. This problem arises when the conveyor speed is variable, for example when it is desired to print without incurring loss time during the time it takes for the conveyor to reach a constant speed from a low speed when it is started. At this time, if the printing speed of the inkjet recording device is constant, a problem arises in that the character width becomes smaller while the conveyor speed is low. To solve this problem, we have adopted a method that changes the printing speed according to the conveyor speed. That is, this is a printing object speed tracking method in which the printing speed is increased as the conveyor speed increases, and the printing speed is decreased as the conveyor speed becomes slow.

This printing object speed tracking method can be realized by detecting the speed of the printing object and varying the printing speed in synchronization with the speed timing. This is accomplished by using a rotary transducer to convert the rotational speed into a pulse signal, and inputting this pulse signal to the printing speed control circuit of the inkjet recording device.
However, with this method, the printing speed of the inkjet recording device is faster than the pulse signal from the rotary transducer. Even if the number of pulses that can be extracted from the conveyor is obtained from the motor shaft that can be extracted at the highest speed, the maximum number of pulses that can be extracted from the conveyor is about 20 KHz. For this reason,
The reality is that the printing speed capability of inkjet recording devices is limited by the performance of the rotary transducer, as it cannot be used on high-speed conveyor lines and would require a very expensive rotary transducer.

One possible way to overcome this inconvenience is to multiply the output pulse frequency of the rotary transducer, but highly accurate multiplication circuits are generally composed of complex analog circuits, resulting in expensive equipment. It was hot.

The object of the present invention is to follow changes in the conveyance speed of a printing medium by multiplying the pulse signal and using it without relying on the performance of a transducer that generates a pulse signal with a frequency proportional to the conveyance speed of the printing medium. Moreover, the multiplier of the pulse signal can be set in detail over a wide range, giving flexibility in the installation location of the transducer, and furthermore, it can be configured with a digital circuit, eliminating the need for complicated adjustment work, making it economical. The goal is to increase reliability.

A feature of the present invention is that it includes means for outputting a pulse signal with a frequency proportional to the conveyance speed of the printing object, and a multiplication circuit that multiplies the frequency of this pulse signal, and prints based on the multiplied pulse signal. In a printing object speed tracking device of an inkjet recording device that controls speed, the multiplication circuit includes a multiplier setting means, a reference clock generation circuit, and generates the reference clock using a value set by the multiplier setting means as a preset value. The first clock counts the reference clock output from the circuit and outputs it every time it reaches a predetermined value.
a counter, an input pulse period detection circuit that detects the period of the pulse signal, a second counter that counts the output signal of the first counter that occurs during the period of the pulse signal, and a second counter. a third counter that counts the reference clock output from the reference clock generation circuit using the count value held in the latch as a preset value and outputs the count value each time a predetermined value is reached; A circuit for outputting a multiplied pulse signal based on the output signal of the third counter is provided, and the pulse signal from the transducer can be multiplied by digital signal processing. Any desired multiplier can be obtained by changing the preset value of the counter.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is a control block diagram of an inkjet recording apparatus to which a printing object speed following device is added.

The speed of the printing object 9, that is, the speed of the conveyor 10, is transmitted from the motor 1 to a rotary transducer 2, which converts the speed of the conveyor 10 into a pulse signal frequency as an electrical signal. The pulse signal is converted by the binarization circuit 3 to the voltage level of the multiplication circuit 4 at the subsequent stage. The multiplication circuit 4 is a circuit that can convert the above-mentioned pulse signal frequency to any multiplication factor over a wide range. The multiplication circuit 4
The frequency amplified by the printing speed control circuit 5
The timing of the printing speed is given to the nozzle control circuit 7 to drive the nozzle control circuit 7. Under the control of the nozzle control circuit 7, ink particles are ejected from the nozzle 8, and characters are printed on the printing object 9.

Now, when the conveyor speed fluctuates, the pulse signal frequency from the rotary transducer 2 similarly changes, and in synchronization with this change, the multiplied signal frequency changes, and the printing speed is adjusted to match the timing of the conveyor speed fluctuation. By changing this, it is possible to obtain printing with a normal character width. Note that 6 is a main control circuit of the inkjet recording apparatus that provides various control information to the nozzle control circuit 7 and the printing speed control circuit 5.

In FIG. 1, the printing object speed tracking device is composed of a rotary transducer 2, a binarization circuit 3, and a multiplication circuit.

FIG. 2 is a control block diagram of one embodiment of the multiplication circuit 4, which is the core of the present invention.

The pulse period of the pulse signal from the binarization circuit 3 is detected by an input pulse period detection circuit 11 and inputted to an input pulse period counting circuit 12 . Also,
The multiplier is set by a multiplier setting switch 13, and the clock pulses from the reference clock generating circuit 15 are counted by a multiplier setting counter circuit 14 using the data set here as a preset value. Here, the pulse signal whose one period is the time counted until overflow is input to the input pulse period counting circuit 12, and only the pulse period detected by the input pulse period detecting circuit 11 is counted. The counted value is held in a counted value holding circuit 16, and this held count value is given as data to a reference clock counting circuit 17, which counts reference clock pulses using this data as a preset value. The reference clock counting circuit 1
The overflow signal of No. 7 is shaped by the next stage pulse duty 1/2 circuit 18 and becomes a multiplied output pulse signal.

The details of the operation principle of the multiplication circuit 4 described above will be explained with reference to an example of an actual circuit shown in FIG. 3 and time charts shown in FIGS. 4 and 5.

The multiplication number is set by switch SW21. In this case, switch SW21 is 8 bits, so
The number of states to be obtained is 256, but since the frequency is halved by the pulse duty 1/2 circuit 18 in FIG. 2, it can be set up to 128 times. D2 of the counter 23 is expressed as the upper digit, A2 as the lower digit, D1 of the counter 22 as the upper digit, and A1 as the lower digit, respectively expressed in binary coded hexadecimal notation.
Expressing the state of the switch SW21 using the lower digits, when the multiplier is set to 9, the frequency is halved by the pulse duty 1/2 circuit 18, so it is 9 x 2.
= 18 and set (ED) _H to switch SW21. (Switch SW21 is negative logic, ( ) _H is binary
Counters 22 and 23 constitute an 8-bit counter by cascading the counters 22 and 23 (hexadecimal number).
-CP1 includes gate circuit, capacitor, resistor,
A reference clock pulse signal (12 MHz in this embodiment) is inputted to an oscillation circuit 20 composed of a crystal resonator.

Counters 22 and 23 count the number of reference pulse signals, and when an overflow occurs, switch SW2 is activated by an L level signal from NAND circuit 24.
1 data (ED) _H is A1 to D of the counter 22
1. It is input to A2 to D2 of the counter 23, and counting is started from this input state.

Therefore, the counters 22 and 23 count the reference clock pulse signal (12MHz) from the set value until it overflows, and in this embodiment, it is counted 18 times and overflows, and the 18/12MHz signal is sent to the next stage from the NAND circuit 24. A periodic pulse signal is output.

Further, the binary output pulse signal of the rotary transducer 2 is input to T1 of the flip-flop 25, and the flip-flop 25, the next stage flip-flop 26, and the NAND circuit 27 convert the output pulse signal from the rotary transducer 2 into the output pulse signal. Period can be detected. The operation of each element at this time is shown in the time chart of FIG.
1,4-4 flip-flop 26-Q2,4-5
This is shown in flip-flop 26-2.

Counters 28 and 29 are connected in cascade,
Operates as an 8-bit counter. A signal from the flip-flop 26-2 is input to the clear inputs C3 and C4 of the counters 28 and 29. That is, the counters 28 and 29 count the pulse signals indicated by 4-1 during the output pulse signal period of the rotary transducer 2 detected in the previous stage. Then, the counted value is held by the next-stage latches 32 and 33. Counters 28, 29, latch 3
The operations of 2 and 33 are shown in 4-6 to 4-12, and 4-
From 6 to 4-9, QA3 to QD3 of counter 28,
4-10 is QA4 of counter 29, 4-11 is QB4 to QD4 of counter 29, and 4-12 is latch 3.
2 and 33 indicate the timings for capturing data of QA3 to QD3 and QA4 to QD4.

The data held in the latches 32 and 33 are inverted and applied to counters 34 and 35 at the next stage. The counters 34 and 35 are 8-bit counters like the counters 22 and 23, and when an overflow occurs, counting is started from data obtained by inverting the data held in the latches 32 and 33. In this example, the retained data is (1F) _H from Figure 4 4-6 to 4-11.
When reversed, it becomes (EO) _H.

The time chart in FIG. 5 shows how the counters 34 and 35 count from data (EO) _H. 5-
1 is the reference clock pulse signal (12MHz), 5-2
Counter 34-CA7, 5-3 Counter 35-CA
8,5-4 NAND circuit 36 output, 5-5 flip-flop 37-Q9. flipflop 3
7 is a pulse duty 1/2 circuit 18 shown in FIG. 2, which solves the problem that the L level time of the output pulse signal obtained in 5-4 is very short.

As a result of the above, when the multiplier is set to 9, the counter 2
2 and 23, 12 MHz pulses are counted 18 times, and these pulses are counted 31 times by counters 28 and 29. In addition, counters 34 and 35 output a 12MHz pulse.
Since it counts 31 times, the output pulse signal of NAND circuit 36 appears 18 times during the rotary transducer 2 output pulse signal period. Therefore, the flip-flop 3 of the pulse duty 1/2 circuit 18
The pulse signal of 7-Q9 is transmitted to rotary transducer 2.
It becomes 9 times the output pulse signal.

As described above, in this embodiment, a multiplier circuit can be realized with a very simple circuit configuration, and the multiplier can be set over a wide range of up to 128 times.

As described above, according to the present invention, the conveying speed of the printed object can be adjusted by multiplying the pulse signal without relying on the performance of the transducer that generates a pulse signal with a frequency proportional to the conveying speed of the printed object. It is possible to follow changes, and the multiplier of the pulse signal can be finely set over a wide range by the preset value to the counter, allowing flexibility in the installation location of the transducer. This eliminates the need for complicated adjustment work and has the effect of increasing economic efficiency and reliability.

[Brief explanation of drawings]

Figure 1 is a block diagram of the printing object speed tracking method.
FIG. 2 is a block diagram of the multiplication circuit, FIG. 3 is a multiplication circuit diagram, and FIGS. 4 and 5 are time charts for explaining FIG. 3. 2... Rotating transducer, 4... Multiplier circuit.

Claims (1)

[Claims] 1 Equipped with a transducer that outputs a pulse signal with a frequency proportional to the conveyance speed of the printed material, and a multiplication circuit that multiplies the frequency of the pulse signal output from the transducer, and generates a multiplied pulse signal. In the printing object speed tracking device of an inkjet recording device that controls the printing speed based on
a reference clock generation circuit 20; and first counters 22 and 23 that count the reference clock output from the reference clock generation circuit using the value set by the multiplier setting means as a preset value and output the count each time a predetermined value is reached. , input pulse period detection circuits 25, 26, and 27 that detect the period of the pulse signal output from the transducer 2, and count output signals of the first counter that occur during the period of the pulse signal. Second counter 28,2
9, and latches 32 and 33 that hold second counter counts, and the count held in these latches is used as a preset value to count the reference clock output from the reference clock generation circuit, and every time a preset value is reached. The third counter 34, 35 outputs to
and a circuit 37 for outputting a multiplied pulse signal based on the output signal of the third counter.